Watch: Footage from the Lame Horse nightclub in Perm shows the chaos as people rushed to escape the fire. Video by Reuters.

(RFE/RL) -- Police today are questioning two owners of a nightclub in the eastern Russian city of Perm, where more than 100 people were killed in an overnight blaze sparked by an indoor firework show.

Authorities say most of the 109 victims were killed by smoke inhalation or crushed in a panic stampede for the only exit at the Lame Horse nightclub. Russia's Emergency Situations Ministry says another 134 people were injured -- about 85 of them critically.

Police say one of the owners is denying allegations that careless handling of fireworks had triggered the blaze.

Initial reports suggested there had been an explosion before the fire. But authorities now say they have ruled out a terrorist attack.

Video footage of the tragedy -- shot by a person who was in the club when the fire began -- shows a fireworks fountain igniting a false ceiling made of highly flammable wicker. The video shows the blaze spreading across the club ceiling within seconds, and captured the ensuing panic as an estimated 233 patrons simultaneously scrambled for the only exit.

The party was hosted by the club owners to celebrate the eighth anniversary of their business. Witnesses said most of those present had been friends or relatives of the owners and staff.

A spokesman of the regional emergencies service said four of the victims died in hospital today. By early afternoon, hospital officials said 85 of the injured remained in critical condition. That has raised fears that the death toll will climb even higher.

Interior Ministry spokesman Valery Gribakin told reporters that that the use of unlicensed fireworks had caused the fire and smoke.

Russian Prime Minister Vladimir Putin ordered a plane to be sent to Perm, about 1,400 kilometers east of Moscow, with additional doctors and medical workers. Another plane of the Emergency Situations Ministry landed in Perm to fly as many as 20 of the injured to Moscow for treatment.

Appeals have been made for blood donations from the 1.2 million residents of Perm. Igor Orlov, the local chief of public safety, said an emergency information center also has been set up for relatives of the victims.

Poor safety standards are often blamed for fires at clubs and other locations in Russia.

Day Of Mourning

Russian President Dmitry Medvedev today called for tough punishment for the nightclub owners, saying "they must be punished with the full force of the law."

Medvedev added that the main owner of the venue had been repeatedly warned by fire inspectors that his premises were unsafe.

The Kremlin says Medvedev has declared December 7 a day of mourning in Russia, with flags to be at half-mast across the nation and the media asked to abstain from light entertainment. Three days of mourning will be observed in Perm.